Single x86-built Assembly Causing entire Assembly to execute as 32-bit - c#

My program (a console application) references several other assemblies (many open-source libraries). I built the assembly with the "Any CPU" option set (using VS2008). When I start the assembly from a 64-bit command prompt on a Windows Server 2008 x64 machine the process always starts as a 32-bit process!
I looked through my references and it appears as though I have a reference for a 32-bit assembly referenced. Could this single reference cause the entire assembly to start as 32-bit?
Also, I use ILMerge to merge all of the referenced assemblies into a single assembly. Maybe that has something to do with it?
Could someone help me figure out what is going on here?

If you need to load a 32bit assembly, the entire process will need to be 32bit. You could target "Any CPU" for your main application, but then it will run 64bit, and fail at runtime when it tries to load the 32bit assembly.
ILMerge is smart enough to switch the main entry assembly from AnyCPU to x86 if you have an x86 assembly as part of your merge, to prevent this from being a problem.
If you want to run 64bit - you'll need to have all of the assemblies be 64bit or AnyCPU.

Yes, this is likely your problem. I would rebuild the assembly as "Any CPU".

Related

If "Any CPU" is selected in Visual Studio, do I still need to separate 32-bit and 64-bit assembly in Advanced Installer?

I'm creating mixed 32-bit/64-bit installers using advance installer, according to this guide Advance Installer Guide for 32-bit/64-bit installers I should seperate 32-bit and 64-bit assemblies. My question is what if my visual studio build is set to "Any CPU", can I use single assembly file for both 32-bit and 64-bit or do I have to create seperate 32-bit and 64-bit assemblies and put them in 32-bit and 64-bit folders in advanced installer.
Additional Information:
My application does not use any DLL references.
You can leave your project building as AnyCPU, and deploy the same assembly to x86 or x64. Advanced Installer's wizard for creating a Mixed Package will ask for files that are x64 only, x86 only, and shared files. Your AnyCPU assembly would be a shared file to deploy for both x86 and x64. Advanced installer puts the shared files in a common component, and the others in their respective 64-bit and 32-bit components.
The Mixed Package uses bootstrapper that contains both an x86 and x64 msi. Another option for deploying your AnyCPU assembly is to create an x86 msi as it would run on both platforms. The x86 msi would deploy your AnyCPU assembly to Program Files (x86), but when run on an x64 machine it would run as an x64 process.
If the assembly uses unmanaged 32- or 64-bit code, you have to compile two respective versions. Otherwise, with "Any CPU" you can use the same assembly for both platforms.
Your project shouldn't go under either of them and should instead likely be put under MainFeature.
The important thing is under Install Parameters you have set the Package Type to "Mixed 32/64-bit matching the platform"

FileNotFoundException (DLL not found)

I'm getting that strange error on one of client's machines. It throws FileNotFoundException, but that DLL is definitely right there in the folder with Executable.. Why it can't find it?
Please advise..
Psychic debugging, since you have not included the full exception details, is that you have a 32bit versus 64bit mismatch:
Your Executable is AnyCPU
The referenced DLL (or a downstream reference) is x86
The machine running the executable is 64bits
Basically, you'll have to recompile your C# executable with a Platform of x86 if you have any x86 DLL dependency (usually an unmanaged DLL).
The assembly may be missing one of its dependent assemblies.

Managed code references between any cpu and x64

I have a mixed-mode C++/CLI project which is compiled as x86 and x64 frozen dlls.
I have a C# app that needs to use this project which is compiled as "Any CPU".
How can I properly reference the correct dll from the c# app?
If I right click add reference I must select only 1 of the 2 dlls.
My "ANY CPU" C# app will sometimes run as x64 and sometimes as x86 process.
I've heard you can maybe do this via a smart config file.
There are several ways to deal with this. First one is simplest, acknowledge the fact that your app actually does have a dependency on the target architecture. And that AnyCPU isn't the proper setting. It is very rare to need the humongous virtual address memory space you get from x64, especially since you also want and need to make it work on x86. So set the Platform target of the EXE to x86 and you're done.
Second is concluding that this is simply a deployment problem. All you have to do is copy the x64 build of the mixed-mode assembly when your app is installed on a 64-bit operating system, the x86 build on a 32-bit operating system. You'll need to create a Setup project that takes care of this. The simplest way is to create two of them. Also the only way afaik.
Third is the one with bells on where it works either way, the one you no doubt are asking about. This requires changes to code, project and installer. What you need to do is write a post-build event that create two subdirectories with names like "x86" and "x64". And copy the respective version of the DLL into them. This ensures that the CLR cannot find these assemblies.
In your code you must write an event handler for the AppDomain.CurrentDomain.AssemblyResolve event. Subscribe it in your Main() method, well before you try to use any types from the assembly. The event handler must use Assembly.LoadFrom() to load the correct assembly from the subdirectory, based on the value of IntPtr.Size. It is 8 when you run in 64-bit mode.
I should mention yet another approach but that's generally frowned-upon at SO. Install both assemblies into the GAC. Everything is automatic.
Even if your C++ project compiles twice it should have the same managed interface for both x86 and x64 DLL's. Hence as long as your not using strong name signing it shouldn't matter which version of the DLL you reference. What's important is that the correct version is deployed on the target machine.

How do I reference a 32 bit DLL in a 64 bit project?

I've got a C# 2.0 project which is set to target 'Any Cpu', however it is referencing a C++ project that's building a 32 bit dll.
When I try to run my program on a 64bit machine I get the following error:
System.BadImageFormatException was
unhandled Message: Could not load file
or assembly TreeTMHook,
Version=1.0.2889.19619,
Culture=neutral, PublicKeyToken=null
or one of its dependencies. An attempt
was made to load a program with an
incorrect format.
How can I fix this?
Update
I want to be able to keep the main project as any cpu.
Thanks.
You'll need to build your .NET project as 32bit (x86 target) if you want it to correctly load a 32-bit DLL on a 64bit machine.
RE: Update:
If you want to keep your project as "Any CPU", you'll need a 32bit and a 64bit version of the DLL, and make sure the appropriate version is distributed with your app. If you can't build the other project as 64bit, you must build your .NET project as 32-bit only.
You will have to force your EXE project to run in 32-bit mode so it can use that C++ DLL. Project + Properties, Build tab, Platform Target = x86.
You may want to take a look at this article it explains why it is not possible, in short since you are dealing with pointers when accessing unmanaged code.
To keep you main project as Any Cpu, you need to supply both 32 and 64 bit version of the .dll - which should be possible, seeing as you're building it from source.
You then need to supply the executable with a manifest pointing it toward to right dll verion depending on platform.
Please use .net reflection and consume objects and its methods. Instead of direct 32 bit dll reference.

Attempt to use DLL results in error

I am using a library (DLL) that uses the Oracle.DataAccess DLL to connect to the database.
I am doing in in C# .NET framework 3.5
When I attempt to compile, the compilation takes place, but the executable throws this error message.
Could not load file or assembly 'Oracle.DataAccess, Version=2.111.7.20, Culture=
neutral, PublicKeyToken=89b483f429c47342' or one of its dependencies. An attempt
was made to load a program with an incorrect format.
Is there some way to get around this? What could be causing this to happen?
The dll for that ODBC is likely a 32bit only dll. Are you using this on a 64bit machine? If you are, IIS 7 has an option in the application pool that will allow you to "Enable 32-Bit Applications".
One possibility: Your programm is compiled with x64 or AnyCPU on a 64bit machine but the dll has been compiled with support for x86 only.
You can overcome this if you change the plattform of your Solution (or project) to x86.
I know you can force a 64bit Assembly to run as a 32bit app with:
corflags /32bit+ Oracle.DataAccess.dll
That works because the MSIL code is not bound to a processor architecture. However I never tried it the other way:
corflags /64bit+ Oracle.DataAccess.dll
so I can't tell if this works. And I propably won't work if the dll has unmanaged dependencies.

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